Information teleportation goes large-scale

Quantum teleportation of information between quantum objects, like photons, is so well-understood that it’s almost routine. Now, an international physicists is claiming to have carried out the same trick in the macro universe.

If the experiment can be replicated, it will be an impressive trick. The scientists, led by Jian-Wei Pen of the University of Science and Technology in Hefei in China, say they’ve teleported quantum state information between ensembles of 100 million rubidium atoms. With a radius of 1 mm across, that’s large enough to be seen with the naked eye.

There’s a good reason for wanting to teleport state between macro objects: they stay where they’re put. Photons, on the other hand, are always on the road, so to speak (unless you apply tricks such as “slow light” to them). That makes a group of atoms much more useful than photons for applications like quantum memory.

The information teleported in the experiment was the spin state of the two rubidium atom ensembles, separated by a 150-meter optical cable (although only half a meter apart in the laboratory).

As described in Phys.org, “To do this, they first mapped the spin wave state of the first atomic ensemble to a propagating photon, and then performed Bell state measurements on that photon and a second photon that was already entangled with the spin wave state of the second atomic ensemble.”

“Once the two photons were projected into an (entangled) Bell state, the quantum information was teleported to the second atomic ensemble.”

The researchers claim an 88 percent success rate for observing the teleportation, with other excitations of the atoms – essentially background noise – limiting the performance of the setup. That success rate, however, is “four orders of magnitude” higher than for a parallel experiment they ran using trapped ions.

The storage lifetime of spin states in the ensembles Pen’s group used was 129 microseconds. The researchers hope to lift this to a more-usable 100 milliseconds, which would allow them to build networks of atomic ensembles transferring information using quantum teleportation.

The research group included scientists from the National Cheng Kung University in Taiwan and Germany’s University of Heidelberg. The work has been published in the Proceedings of the National Academy of Sciences (abstract here).